[time-nuts] Racal-Dana tactile switches

[Charles P. Steinmetz]

Stewart wrote:

>It's a design fault and eventually all of them will fail.

I'm not convinced of that.  There has been substantial discussion of 
Racal switches on the list in the past, and I suggested at one point 
that the failure mechanism (dry, cracked "rubber") could be related 
to the counter manufacturing process -- in particular, soldering 
and/or cleaning of the front panel PCBs.  In my experience with 1992s 
(quite extensive), I have found that (i) in some counters the 
switches never seem to fail, while (ii) if one switch fails in a 
counter, all of the others are not long for the world.  There does 
not (IME) appear to be any correlation with the color of the switch 
body or the markings on the switches.

Then again, I suppose making switches that won't survive every 
possible abuse during whatever soldering and cleaning processes a 
customer might use could be considered a design fault....

Best regards,

Charles